duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
Therefore, about 85-90 percent of children with hereditary retinoblastoma develop multiple tumors that affect both eyes (bilateral disease). The remaining 10-15 percent of patients with hereditary retinoblastoma develop only a single eye tumor (unilateral disease).